The present invention relates generally to fluid storage, and specifically to a method and apparatus for mounting a fluid containment vessel.
In many applications, the qualities of lightweight construction and high resistance to fragmentation and corrosion damage are highly desirable characteristics for a pressure vessel. These design criteria have been met for many years by the development of high pressure composite (fiber reinforced resin matrix) containers; for instance, containers fabricated of laminated layers of wound fiberglass filaments or various types of other synthetic filaments which are bonded together by a thermal-setting or thermoplastic resin. An elastomeric or other non-metal resilient liner or bladder often is disposed within the composite shell to seal the vessel and prevent internal fluids from contacting the composite material.
Such composite vessels have become commonly used for containing a variety of fluids under pressure, such as storing oxygen, natural gas, nitrogen, rocket or other fuel, propane, etc. The composite construction of the vessels provides numerous advantages such as lightness in weight and resistance to corrosion, fatigue and catastrophic failure. These attributes are due to the high specific strengths of the reinforcing fibers or filaments that typically are oriented in the direction of the principal forces in the construction of the pressure vessels.
Composite pressure vessels of the character described above originally were developed for aircraft and aerospace applications primarily because of the critical weight restrictions in such vehicles. As compressed natural gas (CNG) has become more widely used in ground-based vehicles such as buses and cars, however, the composite pressure vessel has become more widely used in such vehicles as well.
The structural requirements of a pressure vessel are such that a generally-cylindrical shape having rounded ends is a highly-desirable form factor from a standpoint of both strength and packing efficiency. Unfortunately, the rounded shape can make securing such a pressure vessel to the vehicle difficult.
The neck of the compressed gas cylinder provides a structural protrusion suitable for attachment by a collar or similar device. Certain known designs make use of this feature to secure a gas cylinder. Unfortunately, such designs suffer from a number of drawbacks. Certain designs handle misalignment poorly, and can place substantial stresses on the neck structure in the event of misalignment. Certain designs inadequately secure the neck, so that there is an unacceptable risk that the cylinder might work itself free under the right conditions. Finally, certain designs are such that the cylinder can rotate about the principal axis of the cylinder, thereby placing stress on the connection lines or other attached hardware.